ci(validate): tools/ 改动不再强制全量 workspace 构建

tools/ 下是离线的描述符生成与发布辅助(tools/compat-*/、tools/gtc/、
publish_mcpp_index.sh),不参与任何包的构建。它们真正影响到某个包时,
生成出的 pkgs/*.lua 会一并变化,而 pkgs 规则已经能精确选中相关成员,
因此 tools/ 单独改动按 docs 处理、不选任何成员。

本 PR 自身即是例子:仅因删除 tools/compat-opencv/ 就把整个 workspace
(含 ffmpeg 与 opencv 的冷构建)在三个平台上全量重跑了一遍。

Author: Sunrisepeak

.github/workflows/validate.yml

@@ -256,8 +256,9 @@ jobs:
       # Run the FULL workspace when the change can affect everything:
       # non-PR events (push to main, the nightly cron, dispatch), this
       # workflow file (it carries the mcpp version pins, so a version bump
-      # always re-validates every package), the workspace manifest, or
-      # shared test scripts. Docs-only changes select nothing.
+      # always re-validates every package), a non-member edit to the
+      # workspace manifest, or shared test scripts. Docs-only and tools/-only
+      # changes select nothing.
       # Note: bash 3.2 on macOS runners — no associative arrays here.
       - name: Select affected workspace members
         shell: bash
@@ -272,7 +273,7 @@ jobs:
           while IFS= read -r f; do
             [ -n "$f" ] || continue
             case "$f" in
-              .github/workflows/validate.yml|tests/*.sh|tools/*) full "$f" ;;
+              .github/workflows/validate.yml|tests/*.sh) full "$f" ;;
               mcpp.toml)
                 # Workspace manifest. Every new-package PR appends to the
                 # members list, so that alone must NOT force a full run:
@@ -298,7 +299,14 @@ jobs:
                   if grep -q "$lib" "$mt"; then add "$(basename "$(dirname "$mt")")"; hit=1; fi
                 done
                 [ "$hit" = 1 ] || echo "note: no workspace member exercises $f" ;;
-              *.md|docs/*|.agents/*|.github/*) : ;;
+              # tools/ holds OFFLINE descriptor-generation and publishing
+              # helpers (tools/compat-*/, tools/gtc/, publish_mcpp_index.sh).
+              # Nothing under it is consumed by a package build: when one of
+              # them actually changes a package, the generated pkgs/*.lua
+              # changes with it and the rule above selects the right members.
+              # So a tools/ edit alone selects nothing rather than forcing a
+              # full workspace rebuild.
+              *.md|docs/*|.agents/*|.github/*|tools/*) : ;;
               *) full "unclassified change: $f" ;;
             esac
           done <<EOF